Reading the Field: dome, comb, and dark zones

Early in a session the Field is a smooth dome, because each strike's influence overlaps its neighbours. Into the close it resolves into a comb of per-strike needles as that influence narrows. Both are the model working, not a rendering glitch.

Dark areas near the flip mean near-zero exposure, not missing data; brightness is distance from the flip. And on cash indices (SPX and friends) the Field freezes at the 4:00 pm cash close, because that's when their options book stops.